Magnetic inspection unit



` the test piece.

Patented Oct. *7, 1941 UNITED 4sTliTrfzs PATENT yo1=`1=icl51 MAGNETIC INSPECTION UNIT 7 Claims.

(ci. rvs-iss) (Granted meer the mi of Marcns, isssgu amended anni so. 192s; 31o o. G. 157) This invention relates to a unit for use in the inspection of cylinders of internal oombustion nany crack, score or similar defect in the piece being tested. As a result, the paramagnetic particles are attracted to these defects and, if the excess iluid be carefully rinsed ofl the piece,- will remain and clearly outline the defects. s Inspection by vthis method gives its best results when the direction of movement of the lar magnetic field and then to a bi-polar field iiowing in a direction parallel to the axis of the i circular eld.

Prior to this invention the means used for conducting the test comprised a grill topped table with a tank beneath, two contact pieces between which the test piece could be clamped after the fashion of work in a lathe, anda hose through which the inspection fluid could betlowed on A hollow coil 'was also provided in which small pieces could be inserted for the portion. of the test involving subjection to a bipolar field. For subjecting larger pieces to inpieces of a certain general shape, in which the test piece may be subjected to both a` circular and a bi-polar magnetic eld.

It is a further object of this invention to pro- .vide an inspection unit which will reduce the time and equipment previously required to make a magnetic inspection. It is a further object of .this invention tc provOther objects will become apparent uponl a consideration of the following description taken together 'with the, accompanying drawing, in which:

Fig. 1 is a side elevational view, partly in sec-` tion, of an inspection unit constructed in accordance with the invention;

Fig. 2 is a plan view of the unit; Fig. 3 is a view of the unit looking from below;

Fig.,4 is a diagrammatic elevational view, in

section, showing the electrical paththrough the unit for creating a circular magnetic ileld;

Fig. 5 is a diagrammatic elevational view in section, showing the electrical path' through the unit for creating a bi-polar magnetic field; and

Fig. 6 is a diagrammatic side elevational view in section showing the path of iluld ow through the unit.

The unit consists of a cylindrical container l mounted upon a base 2 of wood or other insu'- lating material.A The side walls ofv the container consist of an inner wall 3 and an outer wall I, both of copper, betweenwhich is wounda coil 5 of insulated wire. The two ends I and 9 of this coil are attachedtoconnection lugs l andA l which are attached to the wood base on opposite sides of the container. A hollow post hav-l ing copper side walls l0 extends along the axis of the cylindrical container. A copper .plate Il elosesthe top of the hollow post and a copper bolt i'2 passes through said plate and extends downwardly through said hollow post and the wooden base and connects to a copper strip Il.

The latter extends to the .edge Vof said base and has its end turned up to serve' as a connection lug M. A second strip I5 has one end extending upwardly through a holein the base and elec- 'r trically connected-to the inside of the side wall y of the hollow post, as shown at 26. The opposite end of the plate is turned up tol 'form cone nectlon lug Ii. For conveniencethe connection vide ay means for applying inspection iluid to a test piece so that all parts thereof will be continuously and completely covered with fluid during the test. Y f I It is astill further object ot this invention Vto provide a means which will cover a test piece completely with a flood of inspection fluid owing so gently as to prevent a washing action by the uid.

,forms the bottom of the container. Resting upon this and against the container wall 3 is a,` perforated ring of pipe. 20 which is led in through the container wallat 2|.I- 'Ihe outer end 2i of' the pipe serves as a means for connecting it to a hose for supplying inspection iluid. The per- Secured to the top ot the Vmeans of a hose'.

forations 22 are located Vclose to the wall 3 so that inspection fluid will be directed against the wall to avoid excessive rinsing action on the test i container and means associated with said container for producing within it a magnetic field of the circular type and a magnetic field of the f bi-polar type.

` uid containing paramagnetic particles while spected is cleaned and placed in the container j with its bottom supported by the insulated piece I8. The flow of inspection iiuid is now started and one of the two types of magnetic eld is set up. If it be the circular type. the circuit shown in Fig.'4 is utilized with the connection lugs I4 and I6 connected to a source of current.

such as a battery. Current then flows in through I6, through strip I5, up the walls I0 of the holl low post, through the top piece I I, down through bolt I2, and out through strip I3 and lug I4. After the cylinder has been subjected for a short time to this type of magnetization this circuit is through a current source. Here .the current flows through the coil 5 creating a bi-polar field within broken and the one shown in Fig.,5 is completed I it. The iiow of uid is stopped when the current is cut 01T. The piece being inspectedl will be magnetized by this time and-the paramagnetic y particles will be clustered along'all defects, clearly showing their location and shape. The magnetization remaining in the test piece will allow ,careful rinsing of excess fluid from the piece while retaining the defect indications.

The use of this unit allows the application of inspection fluid in a gently owing bath` which is far superior to the use of a hose for flowing it on. Use of the bath insures complete andi-simultaneous coverage of the entire surface 'to bein-I spected, with no strong currents of iiuid to wash oif defect indications. It also allows coverage of inside surfaces which are difilcult tofiiood by The unit also enables the operator to conduct the whole inspection with less apparatus, less manipulation of the piece being inspected, and less time consumed in the operation than has hitherto been required. v

While the disclosure of this invention has been limited to one embodiment of the invention, the scope of the invention is to be considered as restricted only by the scope and limitations ofthe appended c laims.

The invention described herein may be manufactured and/or used by or for the Goverment of. the United States of America for governmental purposes without the payment .of any royalties thereon or therefor. Y

I claim: 1 1. Means for subjecting an object to that process of magnetic inspection which involves flooding the surface of said object with a fluid containing paramagnetic particles while maintainving a magnetic field in said object, said means comprising a containerfor said uid, said-.con-

tainer beingof suiiicient size to contain a sub-v stantial portion of said object, means for filling said container with inspection uid comprising means for directing uid upwardly and. uniformly over the inner surface of the `side walls of said maintaining a magnetic eld in said object,

means for flooding said object with said fluid,

substantial portion of said object, means for lling said container' with inspection uid and maintaining a continuous flow of said iiuid therethrough, said means comprising means for directing fluid upwardly and uniformly over the inner surface of the sidewalls of said-container, and means for conducting away the excess of said fiuid, said meansA having a uid receiving opening located near the axis of said container and at the level at which it is desired that fluid be maintainedtherein.

3. Means for subjecting an object to that process of magnetic inspection which involves iiooding the surface of said object with a fluid containing paramagnetic particles while maintaining a magnetic field in said object, said means comprising a container for said fluid, said container being of suicient size to contain a substantial portion of said object, a coil of insulated' the excess of said fluid, said conduit opening into said container at the level at which it is desired to maintain said fluid. v

4. Means for subjecting an object to that process ofy magnetic inspection which involves flooding the surface of said object with a fluid containing paramagnetic particles while maintaining a magnetic eld in said object, said means comprising a'container for said fluid, said container being of suflicient size to contain a substantial portion of said object, a coil of insulated wire substantially coextensive with the side-walls A.of said container, an elongated current conducting member located within said container and extendingl substantially parallel to the axis thereof, said member comprising a hollow cylinder having one end closed, arod extending from said closed end parallel to and spaced from ythe side-WallsA of said hollow cylinder, means connecting a source of current between the free end vof said rod and the openend of the side-wall of said cylinder. means to connect a source of cur- Vrent across saidcoil, and means for directing said fluid upwardly and uniformly over the inner surface of the side-walls of said container, said cylinder having venting holes located at the level at which it is desired to maintain said fluid in said container.

5. Means forsubjecting an object of generally hollow cylindrical shape to that process of magtainer for said fluid said container being of sumcient size to contain a substantial portion of said object, means for introducing a continuous iiow of said uid through said container from a region near the bottom and adjacent the side lwalls of said container, means to lead oi the excess of said iiuid from said container from a point near the axis of said container and at the level at which it is desired that fluid may he maintained therein, said last named means comprising a hollow elongated cylindrical member having vent openings for said fluid 'formed at said desired level. and means for passing an electrical current through said member in a direction parallel to the axis thereof, thereby subjecting said object to a circular magnetic eld.

6. Means for subjecting an object of generally hollow cylindrical shape to that process of magnetic inspection which involves iiooding the surface of said object with a iluid containing paramagnetic particles, while maintaining a magnetic field in said object, said means comprising a container for said fluid, said container being of suiilcient size to contain a substantial portion of said obiect and being of annular cross-section, a hollow elongated member extending upwardly along l the axis o! said cotnainer from and through the bottom thereof said member being of electrically conductive material and having openings formed therein at the height at which it is desired to maintain the level of said uid in said container and being open at the bottom, whereby it acts as a conduit to carry on the excess of said fluid in said container, a coll of insulating wire wound about the walls of said container, and the means for passing electrical current through said membe!` and said coil at will.

7. Means for` subjecting an object of lgenerally hollow cylindrical shape to that process of magnetic inspection which involves flooding the surface of said object with* a fluid containing'paramagnetic'particles, while mantaining a magnetic s field in said object, said means comprising a `container for said iluidl said container being of sufficient size to contain a substantial portion of said object and being of annular cross-section, a hollow elongated member extending upwardly along the axis of said container from and through the bottom thereof, said member being of electrically conductivematerial and having openings formed therein at the height at which it is desired to maintain the level of said fluid in said container and being open at thebottom, whereby it acts as- 

